Gel insole

ABSTRACT

An insole for insertion into footwear, comprising a forefoot portion, a midfoot portion and a heel portion; the midfoot portion connecting together the forefoot portion and the heel portion; said insole comprising a cushioning layer of a viscoelastic gel material which provides a cushioning function; and wherein the midfoot portion and the heel portion comprise a peripheral edge that curves upwards.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/835,801 filed on Aug. 3, 2006.

BACKGROUND OF THE INVENTION

The present invention relates generally to shoe insoles or inserts, andmore particularly, to gel insoles particularly adapted to providegreater stability within a shoe and to provide greater support to thewearer.

Various types of insoles are known which fit within shoes in order tocorrect various foot problems, alleviate pain and otherwise provide morecomfort to the wearer. Examples of such insoles are those sold by theassignee of the present invention under the trademark Dr. SCHOLL'S®, inparticular those comprised of gel materials as described and claimed inU.S. Pat. No. 6,598,321.

However, it would be useful and desirable to have a full length insoleformed of gel material that includes an upwardly curved edge thatcontacts the outside edge of the foot without constricting the forefoot.In particular, it would be useful and desirable to construct such a fulllength insole where the upwardly curved edge begins at a point behindwhere the ball of the foot contacts the insole, so as to assist inmaintaining contact between the foot and the insole and preventside-to-side movement of the foot on the insole when pressure is exertedon the insole by the foot.

Because of the viscous nature of the gel, the gel insoles provide shockabsorption and consequently protection to the foot. One reason that gelinsoles are popular is that they can be made sufficiently thin to fit inshoes. The most common materials used for making gels are polyurethane,silicone, and thermoplastic rubber. However, because the materials usedto make the gel insoles typically exhibit a high coefficient of frictionupon final manufacture, the resulting insoles have a sticky feel at thesurface. Although this property is beneficial on lower surfaces ofinsoles to keep them in place in shoes, a sticky top surface, whichcontacts the foot, interacts unfavorably with skin or hosiery materials.Fabric can be attached to the top surface of the gel material as a meansto eliminate the problem. However, the additional step of adding thefabric adds cost to the process of making the insole. If a non-fabriccoated gel insole is desired, the gel material can alternatively bedusted, usually with talc, to lower the amount of friction. However, thedusting method is a temporary solution, as the dusting materialtypically separates from the gel material after a prolonged period ofuse, leaving the sticky surface exposed. The dusting method also addscost to the production of insoles.

Moreover it has been surprisingly discovered that an arch support insertcomprising a gel material of a different hardness than the gel materialof the remainder of the insert provides an improvement in arch support,shock absorption and overall comfort.

These and other objectives are satisfied by the invention described andclaimed herein.

SUMMARY OF THE INVENTION

The present invention provides an insole for insertion into footwear,said insole comprising a forefoot portion, a midfoot portion and a heelportion; the midfoot portion connecting together the forefoot portionand the heel portion; said insole comprising a cushioning layer of aviscoelastic gel material which provides a cushioning function; andwherein the midfoot portion and the heel portion comprise a peripheraledge that curves upwards.

The invention also provides an insole for insertion into footwearcomprising a forefoot portion, a midfoot portion and a heel portion;said insole comprising a cushioning layer of a viscoelastic gel materialwhich provides a cushioning function; wherein at least one of theforefoot portion and heel portion comprising at least one substantiallydome shaped pillow protruding from the cushioning layer; and wherein theinsole comprises a peripheral edge that curves upwards at the midfootportion and the heel portion.

In accordance with another aspect of the invention, the insole comprisesa forefoot portion, a mid-foot portion, and a heel portion, saidforefoot portion, mid-foot portion and heel portion being formed by acushioning layer of a resilient material having a first hardness andwhich provides a cushioning function, and a cushioning insert comprisedwithin a recess in said cushioning layer and extending down from saidcushioning layer; said cushioning insert comprising a resilient materialhaving a second hardness that is less than the hardness of saidcushioning layer.

In accordance with another aspect of the present invention, an insolefor insertion into footwear is provided which includes a forefootportion, a mid-foot portion and a heel portion and has a cushioninglayer having upper and lower surfaces; which cushioning layer comprisesa first elastomeric gel material having a first hardness and within arecess in the bottom surface of the cushioning layer a secondelastomeric gel material having a second hardness different from thehardness of the first elastomeric gel material, the second elastomericgel material located substantially in the mid-foot portion to bepositioned below the arch of the foot.

The insole of the invention is a full length insole formed from theforefoot portion, the heel portion and a mid-foot portion connectingtogether the forefoot portion and the heel portion. Preferably, thecushioning layer extends through the forefoot portion, heel portion andmid-foot portion. Preferably, at least one of the forefoot portion andheel portion includes at least one substantially dome shaped pillowprotruding down from the cushioning layer thereat.

Preferably the cushioning layer and the pillow(s) are formed from thesame viscoelastic gel material as a unitary, one-piece structure. In analternative embodiment, the pillow(s) are formed from a foam material.

The insole further may comprise an arrangement for maintaining theinsole in position in the footwear when the insole is in use. Thearrangement can comprise, for example, an adhesive at a lower surface ofthe insole, for example a non-permanent adhesive that permits removal ofthe insole from the footwear and repositioning the insole in thefootwear, or alternatively, a high friction lower surface of the insole.

In another embodiment, the arrangement for maintaining the insole inposition includes a tackifier added to the gel material. Preferably, thegel material forming the dome shaped pillow(s) comprises a plurality ofspaced apart spring walls formed from the viscoelastic gel, the springwalls extending from a lower surface of the cushioning layer. In oneembodiment, the spring walls have a height which is greatest at a centerof the pillow and which tapers in height toward edges of the pillow.Preferably, each of the spring walls is formed in a generally sinusoidalwave shape.

Preferably, the cushioning layer has a substantially uniform thicknessof about 2 mm and the pillow(s) have a height less than about 3 mm abovethe uniform layer.

The invention further comprises a top cover which can be secured to anupper surface of the cushioning layer. Preferably the top cover is amade of a low friction film material, which preferably comprises astyrenic block copolymer.

The invention also provides a method for constructing a gel insolecomprising a viscoelastic gel material to comprise a low friction topsurface, which method comprises the steps of placing a film materialcomprising a styrenic block copolymer and having top and bottom surfacesin an injection mold, and injecting viscoelastic gel material into themold to form the gel insole on the bottom surface of the film material,thereby providing the low friction top surface for the gel insoles.

The above and other features of the invention will become readilyapparent from the following detailed description thereof which is to beread in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a left insole according to oneembodiment of the present invention;

FIG. 2 is a top plan view of the left insole;

FIGS. 3A and 3B are bottom plan views of the left and right insoles,respectively, according to one embodiment;

FIG. 4 is a side elevational view of the right insole;

FIG. 5 is perspective view of one embodiment of a right insole showingcombination of gel film top cover and cloth top cover;

FIG. 6 is top and bottom view of an embodiment of insoles showing firstand second gels of different hardness;

FIG. 7 is perspective view of one embodiment of a right insole showingcombination of gel film top cover and cloth top cover;

FIG. 8 is perspective view of one embodiment of a left insole showingcombination of gel film top cover and cloth top cover.

DETAILED DESCRIPTION

Referring to the drawings in detail, and initially to FIGS. 1-4 thereof,a left insole 10 according to a first embodiment of the presentinvention is adapted to be placed in an article of footwear, as is wellknown. A right insole (depicted in FIG. 3B) is identical to left insole10 and is a mirror image thereof.

As depicted in FIGS. 1 and 2, insole 10 is designed to fit the shape ofa human left foot and therefore includes a curved toe or forefootportion 12, a heel portion 14, and a mid-foot portion 16 which connectsforefoot portion 12 and heel portion 14 together. Cushioning layer 18,preferably generally planar throughout most of the insole, curves upwardat the peripheral edges of the midfoot portion 30 and heal portion 32 ofthe insole in order to create a cradle for the side, heel and arch ofthe foot.

In one embodiment shown in FIGS. 3A and 3B, insole 10 comprises a pillow20 extending from the lower surface of cushioning layer 18 at forefootportion 12 and a generally dome shaped, lower pillow 22 extending fromthe lower surface of cushioning layer 18 at heel portion 14. Preferably,pillows 20, 22 are generally dome shaped.

As depicted in FIG. 4, cushioning layer 18 and pillows 20 and 22 areformed as a unitary, one-piece layer of the same viscoelastic gelmaterial. In an alternative embodiment, the pillows 20 and 22 are formedfrom a different material that the viscoelastic gel material of thecushioning layer 18. Specifically, in said alternative embodiment,pillows 20 and 22 can be made from a resilient foam material thatprovides a conventional cushioning function. As such, pillows 20 and 22form a typical foam mechanical spring, shock absorption layer thatcushions the foot, in order to decrease pressure. Cushioning layer 18 ispreferably made from non-foam elastomers such as the class of materialsknown as viscoelastic gel polymers as described in U.S. Pat. No.6,598,321, which show high levels of damping when tested by dynamicmechanical analysis performed in the range of −50° C. to 100° C. Becausethe mechanical properties of the gel are more viscous than elastic, thegel provides a high energy absorption. Gels that can be used accordingto the present invention are thermoplastic elastomers (elastomericmaterials), such as materials made from many polymeric families,including but not limited to the Kraton family of styrene-olefin-rubberblock copolymers, thermoplastic polyurethanes, thermoplastic polyolefins, polyamides, polyureas, polyesters and other polymer materialsthat reversibly soften as a function of temperature. The preferredelastomer is a Kraton block copolymer ofstyrene/ethylene-co-butylene/styrene or styrene/butadiene/styrene withmineral oil incorporated into the matrix as a plasticizer. In oneembodiment, cushioning layer 18 can be a laminate construction, that is,a multilayered composite of any of the above materials. Multilayeredcomposites are made from one or more of the above materials such as acombination of polyethylene vinyl acetate and polyethylene (two layers),a combination of polyurethane and polyvinyl chloride (two layers) or acombination of ethylene propylene rubber, polyurethane foam and ethylenevinyl acetate (3 layers).

When made of a different material than cushioning layer 18, pillows 20and 22 can be made from any suitable material including, but not limitedto, any flexible material which can cushion and absorb the shock fromheel strike on the insole. Suitable shock absorbing materials caninclude any suitable foam, such as but not limited to, cross-linkedpolyethylene, poly(ethylene-vinyl acetate), polyvinyl chloride,synthetic and natural latex rubbers, neoprene, block polymer elastomerof the acrylonitrile-butadiene-styrene or styrene-butadiene-styrenetype, thermoplastic elastomers, ethylenepropylene rubbers, siliconeelastomers, polystyrene, polyurea or polyurethane; most preferably apolyurethane foam made from flexible polyol chain and an isocyanate suchas a monomeric or prepolymerized diisocyanate based on4,4′-diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI).Such foams can be blown with freon, water, methylene chloride or othergas producing agents, as well as by mechanically frothing to prepare theshock absorbing resilient layer. Such foams advantageously can be moldedinto the desired shape or geometry.

The materials of cushioning layer 18 and pillows 20 and 22 can beprepared by conventional methods such as heat sealing, ultrasonicsealing, radio-frequency sealing, lamination, thermoforming, reactioninjection molding, and compression molding and, if necessary, followedby secondary die-cutting or in-mold die cutting. Representative methodsare taught, for example, in U.S. Pat. Nos. 3,489,594; 3,530,4894,257,176; 4,185,402; 4,586,273, in the Handbook of Plastics, Herber R.Simonds and Carleton Ellis, 1943, New York, N.Y., Reaction InjectionMolding Machinery and Processes, F. Melvin Sweeney, 1987, New York,N.Y., and Flexible Polyurethane Foams, George Woods, 1982, New Jersey,whose preparative teachings are incorporated herein by reference. Forexample, the innersole can be prepared by a foam reaction moldingprocess such as taught in U.S. Pat. No. 4,694,589.

In the embodiment shown in FIGS. 3A and 3B and FIG. 4, pillows 20 and 22extend downwardly below the lower surface of cushioning layer 18 toprovide extra cushioning at the ball of the foot area of forefootportion 12 and at heel portion 14. In equally preferred embodiments, thearrangement of the material can result in the pillows protruding upwardfrom the surface of cushioning layer 18. Preferably, cushioning layer 18has a constant thickness throughout. For example, cushioning layer 18can have a thickness of about 2 mm and the pillow 20 or 22 preferablyhaving a thickness of about 3 mm. Thus, the combined thickness ofcushioning layer and any pillow 20 or 22 would preferably have athickness of about 5 mm.

As depicted in FIG. 5 top cover layer 24 can be secured to the uppersurface of cushioning layer 18, although such a top cover layer 24 isnot required. In such case, top cover layer 24 can be made from anysuitable material including, but not limited to, fabrics, leather,leatherboard, expanded vinyl foam, flocked vinyl film, coagulatedpolyurethane, latex foam on scrim, supported polyurethane foam,laminated polyurethane film or in-mold coatings such as polyurethanes,styrene-butadiene-rubber, acrylonitrile-butadiene, acrylonitrileterpolymers and copolymers, vinyls, or other acrylics, as integral topcovers. Desirable characteristics of top cover layer 24 include gooddurability, stability and visual appearance. It is also desirable thattop cover layer 24 have good flexibility, as indicated by a low modulus,in order to be easily moldable. The bonding surface of top cover layer24 should provide an appropriate texture in order to achieve a suitablemechanical bond to the upper surface of cushioning layer 18. Preferably,the material of top cover layer 24 is a fabric, such as a brushed knitlaminate top cloth (brushed knit fabric/urethane film/non-woven scrimcloth laminate) or a urethane knit laminate top cloth. Preferably, topcover layer 24 is made from a polyester fabric material, and preferablyhas a thickness of about 0.02 inch.

Preferably the insoles of the present invention comprise a top cover 24comprising a self adhesive low friction film material 26. The filmmaterial is chosen to be compatible with the gel material that comprisesthe remainder of the insole, described above. In one embodiment, thefilm material comprises a polyurethane when the gel material in theinsole comprises polyurethane. In another embodiment, the film materialcomprises a styrenic block copolymer, such as the Kraton block copolymerof styrene/ethylene-co-butylene/styrene (SEBS) orstyrene/butadiene/styrene (SBS) described above for the cushioning layer18 when the gel material in the insole comprises styrenic blockcopolymers. As explained above, these copolymers comprise mineral oilincorporated into the matrix as a plasticizer, typically in high contentof the gels, such as greater than 50%, and in some embodiments greaterthan 70% by weight and can be difficult to mechanically attach woven topcloth to the upper surface. It has been found that a gel film materialcomprising a styrenic block copolymer such as SEBS with mineral oil andpolypropylene produces a suitable film material that can be added to aninjection mold before the mold is loaded with the gel material to formthe cushioning layer 18, thereby providing the low friction gel film topcover for the gel insoles of the invention. In certain embodiments, thegel film top cover can cover the entire top surface of the gel insole orcan comprise only portions of the top surface. Thus, for example, asdepicted in FIGS. 5-8, the gel film top cover can be used in addition tothe other top surface material described above, whereby part of the topsurface of the insole is a woven fabric or other material and part ofthe top surface is a gel film top cover. In certain embodiments, the gelfilm top cover will comprise only certain higher pressure points such asthose areas of the insole 10 that will come in contact with the toes,ball of foot, and/or heel. Because the gel material of certainembodiments of insole 10 and the gel film top covers are substantiallytranslucent, the arrangement of partial gel film top cover portions canbe made to provide a decorative pattern as well.

As depicted in FIG. 6, in a further embodiment of the invention,cushioning layer 18 comprises a first elastomeric gel material 40 havinga first hardness and within a recess in the bottom surface of thecushioning layer a second elastomeric gel material 42 having a secondhardness different from the hardness of the first elastomeric gelmaterial, the second elastomeric gel material located substantially inthe mid-foot portion, preferably to be positioned below the arch of thefoot. In a preferred embodiment, the first elastomeric gel material hasa greater hardness than the second elastomeric gel material. For examplethe first elastomeric material may have a Shore OO hardness of betweenabout 50 to about 65, preferably between about 55 to about 65, mostpreferably about 55. The second elastomeric gel material may have aShore OO hardness of between about 30 to about 45, preferably betweenabout 40 to about 45, most preferably about 45.

It will be appreciated that insole 10 is a full length insole extendingalong the entire foot. Typically, insole 10 would be sized correspondingto shoe sizes and would be provided in sized pairs. Alternatively,insole 10 may be trimmed to the requirements of the user. In thisregard, arcuate pattern trim lines (not shown) may be formed on thelower surface of forefoot portion 12 of insole 10, which arerepresentative of various sizes of the human foot. The pattern trimlines may be imprinted by conventional printing techniques,silkscreening and the like. As an alternative, the pattern trim linesmay be formed as shallow grooves, or be perforated, so that a smallersize insole may be separated by tearing along the appropriate trimlines, which tearing operation is facilitated by the inclusion ofperforations. Thus, forefoot portion 12 can be trimmed so that forefootportion 12 fits within the toe portion of open style footwear.

Alternatively, a pattern trim line can be provided on the lower surfaceof cushioning layer 18 to cut around the thong of some types of openstyle footwear, if necessary.

In order to secure insole 10 to footwear, an area of adhesive 26, forexample, by a double sided adhesive tape, is formed along the length ofthe lower surface of cushioning layer 18, and is covered by a releasesheet 28. In this manner, a user merely removes release sheet 28 andadheres insole 10 to the footwear. Adhesive 26 can be a permanentadhesive or a release adhesive that permits removal and reapplying orrepositioning of insole 10 in the footwear.

Alternatively, lower surface of cushioning layer 18 can be provided as ahigh friction surface to maintain insole 10 in position in the footwear.For example, synthetic rubber adhesive coating (not shown) can be addedto lower surface 18 a of cushioning layer 18 for this purpose.

Accordingly, with insole 10, cushioning pillows 20 and 22 are providedat the ball of the foot area of forefoot portion 12 and at heel portion14 where most of the impact and forces occur during a gait. Further,such insole 10 fits within footwear, and will remain in position in suchopen style footwear during wearing by the user. Moreover, because of theupward curvature of the peripheral edges, the wearer experiences a moresecure fit between the foot and insole, thereby enhancing comfort to thewearer.

Insole 10 can be also be secured to the footwear by using the tackproperties of the gel. In this regard, it is preferred that the tack ofthe gel is enhanced by incorporating a tackifier into the gelcomposition to increase the friction/tack of the gel surface. Suitabletackifiers include a petroleum hydrocarbon resin sold under thedesignation I-Mark V by Idemitsu Kosan Co., Ltd. of Tokyo, Japan; therosin sold under the trademark ASYLVALITE® under designation RE 80 forSEBS gels; and phenolsulfonic acid ester sold under the trademarkAMESAMOLL® for a polyurethane (PU) gel. The desired tack is preferablybetween 120 and 250 grams, as determined by a probe tack tester soldunder the trademark APOLYKEN®, at one second contact time.

Although the present invention uses the term insole, it will beappreciated that the use of other equivalent or similar terms such asinnersole or insert are considered to be synonymous and interchangeable,and thereby covered by the present claimed invention.

Having described specific preferred embodiments of the invention withreference to the accompanying drawings, it will be appreciated that thepresent invention is not limited to those precise embodiments and thatvarious changes and modifications can be effected therein by one ofordinary skill in the art without departing from the scope or spirit ofthe invention as defined by the appended claims.

1.-45. (canceled)
 46. An insole for insertion into footwear, said insolecomprising a forefoot portion, a midfoot portion and a heel portion; themidfoot portion connecting together the forefoot portion and the heelportion; said insole comprising a cushioning layer of a viscoelastic gelmaterial which provides a cushioning function; wherein the cushioninglayer is formed as a one-piece structure; wherein the midfoot portionand the heel portion comprise a peripheral edge that curves upwards; andwherein at least one of said forefoot portion and said heel portioncontains a substantially dome shaped pillow protruding from saidcushioning layer thereat wherein said substantially dome shapedpillow(s) comprise a plurality of spaced apart spring walls formed fromsaid viscoelastic gel, said spring walls extending from a lower surfaceof said cushioning layer wherein said spring walls each have a heightwhich is greatest at a center of said pillow and which tapers in heighttoward edges of said pillow.
 47. An insole according to claim 46,wherein said cushioning layer and said substantially dome shapedpillow(s) are formed from the same viscoelastic gel material as aunitary, one-piece structure.
 48. An insole according to claim 46,wherein said insole contains an arrangement for maintaining said insolein position in said footwear during use.
 49. An insole according toclaim 48, wherein said arrangement comprises providing a high frictionmaterial on a surface of the insole that contacts said footwear.
 50. Aninsole according to claim 49, wherein said high friction materialcomprises an adhesive applied to at least a portion of a surface of theinsole that contacts the footwear.
 51. An insole according to claim 50,wherein said adhesive is a release adhesive that permits removal of theinsole from the footwear and repositioning the insole in the footwear.52. An insole according to claim 49, wherein said high friction materialcomprises tackifier material added to said viscoelastic gel material.53. An insole according to claim 46, wherein each of said spring wallsis formed in a generally sinusoidal wave shape.
 54. An insole accordingto claim 46, wherein said cushioning layer has a substantially uniformthickness of about 2 mm
 55. An insole according to claim 46, whereinsaid substantially dome shaped pillow(s) have a height less than about 3mm.
 56. An insole according to claim 46, further comprising a top coversecured to an upper surface of said cushioning layer.
 57. An insoleaccording to claim 56, wherein the top cover comprises a low frictionfilm material.
 58. An insole according to claim 57, wherein the lowfriction film material comprises a styrenic block copolymer.
 59. Theinsole according to claim 58, wherein the low friction film materialcomprises a copolymer chosen from the group consisting ofstyrene/ethylene-co-butylene/styrene (SEBS), styrene/butadiene/styrene(SBS) and mixtures of styrene/ethylene-co-butylene/styrene (SEBS),styrene/butadiene/styrene (SBS).
 60. An insole according to claim 57,wherein the low friction film material consists essentially of SEBS,mineral oil and polypropylene.
 61. An insole comprising a forefootportion, a mid-foot portion, and a heel portion, said forefoot portion,mid-foot portion and heel portion forming a cushioning layer comprisinga resilient material having a first hardness and which provides acushioning function, and a cushioning insert comprised within a recessin said cushioning layer and extending down from said cushioning layer;said cushioning insert comprising a resilient material having a secondhardness that is less than the hardness of said cushioning layer.
 62. Aninsole for insertion into footwear comprising a forefoot portion, amid-foot portion and a heel portion forming a cushioning layer havingupper and lower surfaces; which cushioning layer comprises a firstelastomeric gel material having a first hardness and a secondelastomeric gel material having a second hardness less than the hardnessof the first elastomeric gel material, said second elastomeric gelmaterial disposed within a recess in the bottom surface of thecushioning layer, the recess located substantially in the mid-footportion positioned below the arch of the foot.
 63. An insole accordingto claim 57, wherein the insole comprises said low friction filmmaterial on at least one of said forefoot portion, said midfoot portionand said heel portion.
 64. The insole according to claim 46 wherein saidgel material curves upward at the peripheral edge.